RX7SIGN

Man my car has been running flawlessly for like a year almost. I recently cleaned my intake maybe making a few more hp like 2 or 3.. Now randomly my car is boosting late any explanation? I reset the ecu but it didnt fix anything. It seems its switching over at 5,500 instead of 4,500.


PS. My sweet point before this was right after switchover 5k or 5,500k..Now when I do that I get no boost as if im inbetween switchover not building boost. Now to make boost I have to be at like 6k or 6,600k..how could the switchover point change. I take very good care of this rotary I dont know wtf is up..

moconnor

iTrader: (14)

What is your boost pattern?

Could be low transition but without knowing the boost pattern it is hard to judge.

htharv

is it hesitating too? you did any mods on the car, or is it stock?

RX7SIGN

Yeah it is hesitating..I have hks exhuast & dp..and apexi intake

htharv

http://www.autosportracetech.com/RX-...leshooting.htm
I think this could help...

htharv

my guess is you have a leak in your vacuum system... or a sticky solenoid valve, I'd check the charge control valve first...

RX7SIGN

My charge control valve? How would I check it?

moconnor

iTrader: (14)

Eh, the link two posts up has a detailed procedure for testing it. Did you read it?

RX7SIGN

Yeah i see you can interchange them etc. im thinking my problem is elsewhere im gonna take some things apart see what i can do. Someone told me it might be the rat nest aka solenoid city

dgeesaman

iTrader: (7)

The transition point cannot change; it is controlled by the ECU. One of the components that needs to activate at 4500 can be slow or not respond, but that causes a dip between 4500 and whenever it finally responds (if at all).

What exactly is your boost pattern? Do you get boost between 3000 and 4500? At 4500, what is your boost, and then what happens above 4500?

As for the Charge Control Valve, yes if the valve is sticking or the solenoid isn't functioning right it can affect the release of secondary boost into the intake. This is the valve on the y-pipe, and you can verify it's function using the KOKO test (http://www.fd3s.net/boost_test.html). This test also tests the turbo control valve, which is vital to boosting above 4500.

The Charge Control Valve is the 3rd component active at the transition. It goes from open to closed at 4500, and stops dumping the secondary boost to the airbox. If it is slow or the solenoid controlling it is sticking, you'll have a reduced boost above 4500 until the valve shuts again. The best test for this (IMO) is to disconnect it from the airbox and let it dump into the engine bay. It's ok to do this for just a couple test runs only. Listen for the sound of it venting air - it should stop crisply at 4500. Any noise above 4500 is the sound of lost boost.

Dave

RX7SIGN

After 4,500 there is no secondary kick it comes in around 5,500k. At 4,500k it should switchover and deliver good power however it doesnt. First gear doesnt see boost until almost 6 and the boost pattern is low. It doesnt switchover until past 5,000k. I will take it PF and see what he can do. .

correction: the boost pattern is irrelovant in my situation. The boost pattern is nearly the same and holding correct boost its just occuring later which means the transition is being delayed due to something that controls switchover..

RX7SIGN

Forget the last thing I posted it didnt make sense..

What im trying to say is it isnt switching over correctly..

DaveW

You may have a check valve malfunctioning or a loose hose on the pressure tank circuit. The turbo actuator uses both vacuum and pressure to actuate, and if pressure is absent, it will be VERY slow. The solenoid valve which sends this pressure to the turbo actuator may also be bad.

dgeesaman

iTrader: (7)

Run the KOKO test then.

Dave

RX7SIGN

KOKO unplug the crv piping from my intake and look for the sound after 4,500?

maxcooper

I had an issue once where the valve in the y-pipe (throttle valve in pipe, actuator located on top of the y-pipe, accessible from the top) was sticking. It made the transition slow, much like you describe here. The valve would hang up as the switch-over occurred. You can test it by disconnecting the vacuum hose from the actuator and using another hose and your lungs to test if it actuates the valve smoothly. Mine would get stuck in the middle, so I replaced the valve (since I had another one around). Perhaps some cleaning and/or lube could fix one without replacement.

-Max

-Max

RX7SIGN

Okay I guess I will look for a diagram to see if I can find the y-pipe and do this procedure..Thanks alot

dgeesaman

iTrader: (7)

The test where you listen for the CRV closing at 4500 is one test. Then reconnect it if it's shutting off at 4500.

The next test is the KOKO test. If you have a helper, they can watch the Charge Control Valve (that's the one on the Y-pipe Max is referring to) and be sure that it doesn't just move, but moves quickly. Alternate to Max's test, you can also reach in (engine cold!) and move the valve with your finger. If it's sticking you'll feel it not move smoothly.

Dave

7THSIGN

Your solution to this problem, take it to Ray and let him fix it in a day. Lets learn from the last problem we had with the car… the coil.